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The evolution of the Silver Hills Volcanic Center, and revised 40Ar/39Ar geochronology of Montserrat, Lesser Antilles, with Implications for island arc volcanism

The evolution of the Silver Hills Volcanic Center, and revised 40Ar/39Ar geochronology of Montserrat, Lesser Antilles, with Implications for island arc volcanism
The evolution of the Silver Hills Volcanic Center, and revised 40Ar/39Ar geochronology of Montserrat, Lesser Antilles, with Implications for island arc volcanism
Studying the older volcanic centers on Montserrat, Centre Hills and Silver Hills, may reveal how volcanic activity can change over long time periods (≥1 Myr), and whether the recent activity at the Soufrière Hills is typical of volcanism throughout Montserrat's history. Here, we present the first detailed mapping of the Silver Hills, the oldest and arguably least studied volcanic center on Montserrat. Volcanism at the Silver Hills was dominated by episodic andesite lava dome growth and collapse, produced Vulcanian style eruptions, and experienced periodic sector collapse events, similar to the style of volcanic activity that has been documented for the Centre Hills and Soufrière Hills. We also present an updated geochronology of volcanism on Montserrat, by revising existing ages and obtaining new 40Ar/39Ar dates and palaeomagnetic ages from marine tephra layers. We show that the centers of the Silver, Centre, and Soufrière Hills were active during at least ∼2.17–1.03 Ma, ∼1.14–0.38 Ma, and ∼0.45 Ma–present, respectively. Combined with timings of volcanism on Basse-Terre, Guadeloupe these ages suggest that ∼0.5–1 Ma is a common lifespan for volcanic centers in the Lesser Antilles. These new dates identify a previously unrecognized overlap in activity between the different volcanic centers, which appears to be a common phenomenon in island arcs. We also identify an older stage of Soufrière Hills activity ∼450–290 ka characterized by the eruption of hornblende-orthopyroxene-phyric lavas, demonstrating that the petrology of the Soufrière Hills eruptive products has changed at least twice throughout the volcano's development.
1525-2027
Hatter, S. J.
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Palmer, M.R.
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Gernon, T. M.
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Taylor, R. N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Cole, P. D.
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Barfod, D. N.
443dd9b7-8319-47ef-8e18-f6f7e43a0a6b
Coussens, M.
761d9bfc-bb42-4362-b5cd-91cbc85b53a5
Hatter, S. J.
b43a8c1b-8ae3-4764-8238-3dc597aa0d71
Palmer, M.R.
d2e60e81-5d6e-4ddb-a243-602537286080
Gernon, T. M.
658041a0-fdd1-4516-85f4-98895a39235e
Taylor, R. N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Cole, P. D.
20e989bb-2d0d-4c1a-a7b1-e83296fd1487
Barfod, D. N.
443dd9b7-8319-47ef-8e18-f6f7e43a0a6b
Coussens, M.
761d9bfc-bb42-4362-b5cd-91cbc85b53a5

Hatter, S. J., Palmer, M.R., Gernon, T. M., Taylor, R. N., Cole, P. D., Barfod, D. N. and Coussens, M. (2018) The evolution of the Silver Hills Volcanic Center, and revised 40Ar/39Ar geochronology of Montserrat, Lesser Antilles, with Implications for island arc volcanism. Geochemistry, Geophysics, Geosystems. (doi:10.1002/2017GC007053).

Record type: Article

Abstract

Studying the older volcanic centers on Montserrat, Centre Hills and Silver Hills, may reveal how volcanic activity can change over long time periods (≥1 Myr), and whether the recent activity at the Soufrière Hills is typical of volcanism throughout Montserrat's history. Here, we present the first detailed mapping of the Silver Hills, the oldest and arguably least studied volcanic center on Montserrat. Volcanism at the Silver Hills was dominated by episodic andesite lava dome growth and collapse, produced Vulcanian style eruptions, and experienced periodic sector collapse events, similar to the style of volcanic activity that has been documented for the Centre Hills and Soufrière Hills. We also present an updated geochronology of volcanism on Montserrat, by revising existing ages and obtaining new 40Ar/39Ar dates and palaeomagnetic ages from marine tephra layers. We show that the centers of the Silver, Centre, and Soufrière Hills were active during at least ∼2.17–1.03 Ma, ∼1.14–0.38 Ma, and ∼0.45 Ma–present, respectively. Combined with timings of volcanism on Basse-Terre, Guadeloupe these ages suggest that ∼0.5–1 Ma is a common lifespan for volcanic centers in the Lesser Antilles. These new dates identify a previously unrecognized overlap in activity between the different volcanic centers, which appears to be a common phenomenon in island arcs. We also identify an older stage of Soufrière Hills activity ∼450–290 ka characterized by the eruption of hornblende-orthopyroxene-phyric lavas, demonstrating that the petrology of the Soufrière Hills eruptive products has changed at least twice throughout the volcano's development.

Text Hatter et al G-cubed 2nd February 2018 - accepted version
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Text Hatter et al 2018 accepted manuscript
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Accepted/In Press date: 20 January 2018
e-pub ahead of print date: 1 February 2018

Identifiers

Local EPrints ID: 417566
URI: https://eprints.soton.ac.uk/id/eprint/417566
ISSN: 1525-2027
PURE UUID: 7542db81-147a-4f4b-b415-591bcfc751c6
ORCID for S. J. Hatter: ORCID iD orcid.org/0000-0003-0760-5275

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Date deposited: 05 Feb 2018 17:30
Last modified: 15 Jun 2018 00:27

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Contributors

Author: S. J. Hatter ORCID iD
Author: M.R. Palmer
Author: T. M. Gernon
Author: R. N. Taylor
Author: P. D. Cole
Author: D. N. Barfod
Author: M. Coussens

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